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Two changes:

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1. Fold  [mem] += (1|-1) into inc [mem]/dec [mem] to save some icache space.
 2. Do not let token factor nodes prevent forming '[mem] op= val' folds.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19643 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-01-17 22:10:42 +00:00
parent a651cf67b7
commit 5c65981a57
1 changed files with 74 additions and 5 deletions
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79
lib/Target/X86/X86ISelPattern.cpp
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@ -2242,18 +2242,51 @@ bool ISel::TryToFoldLoadOpStore(SDNode *Node) {
assert(Node->getOpcode() == ISD::STORE && "Can only do this for stores!");
SDOperand Chain = Node->getOperand(0);
SDOperand StVal = Node->getOperand(1);
SDOperand StPtr = Node->getOperand(2);
// The chain has to be a load, the stored value must be an integer binary
// operation with one use.
if (Chain.getOpcode() != ISD::LOAD || !StVal.Val->hasOneUse() ||
StVal.Val->getNumOperands() != 2 ||
if (!StVal.Val->hasOneUse() || StVal.Val->getNumOperands() != 2 ||
MVT::isFloatingPoint(StVal.getValueType()))
return false;
SDOperand TheLoad = Chain.getValue(0);
// Token chain must either be a factor node or the load to fold.
if (Chain.getOpcode() != ISD::LOAD && Chain.getOpcode() != ISD::TokenFactor)
return false;
// Check to see if we are loading the same pointer that we're storing to.
if (TheLoad.getOperand(1) != Node->getOperand(2))
SDOperand TheLoad;
// Check to see if there is a load from the same pointer that we're storing
// to in either operand of the binop.
if (StVal.getOperand(0).getOpcode() == ISD::LOAD &&
StVal.getOperand(0).getOperand(1) == StPtr)
TheLoad = StVal.getOperand(0);
else if (StVal.getOperand(1).getOpcode() == ISD::LOAD &&
StVal.getOperand(1).getOperand(1) == StPtr)
TheLoad = StVal.getOperand(1);
else
return false; // No matching load operand.
// We can only fold the load if there are no intervening side-effecting
// operations. This means that the store uses the load as its token chain, or
// there are only token factor nodes in between the store and load.
if (Chain != TheLoad.getValue(1)) {
// Okay, the other option is that we have a store referring to (possibly
// nested) token factor nodes. For now, just try peeking through one level
// of token factors to see if this is the case.
bool ChainOk = false;
if (Chain.getOpcode() == ISD::TokenFactor) {
for (unsigned i = 0, e = Chain.getNumOperands(); i != e; ++i)
if (Chain.getOperand(i) == TheLoad.getValue(1)) {
ChainOk = true;
break;
}
}
if (!ChainOk) return false;
}
if (TheLoad.getOperand(1) != StPtr)
return false;
// Make sure that one of the operands of the binop is the load, and that the
@ -2333,6 +2366,9 @@ bool ISel::TryToFoldLoadOpStore(SDNode *Node) {
}
if (Opc) {
LoweredTokens.insert(TheLoad.getValue(1));
Select(Chain);
X86AddressMode AM;
if (getRegPressure(TheLoad.getOperand(0)) >
getRegPressure(TheLoad.getOperand(1))) {
@ -2343,6 +2379,36 @@ bool ISel::TryToFoldLoadOpStore(SDNode *Node) {
Select(TheLoad.getOperand(0));
}
if (StVal.getOpcode() == ISD::ADD) {
if (CN->getValue() == 1) {
switch (Op0.getValueType()) {
default: break;
case MVT::i8:
addFullAddress(BuildMI(BB, X86::INC8m, 4), AM);
return true;
case MVT::i16: Opc = TabPtr[1];
addFullAddress(BuildMI(BB, X86::INC16m, 4), AM);
return true;
case MVT::i32: Opc = TabPtr[2];
addFullAddress(BuildMI(BB, X86::INC32m, 4), AM);
return true;
}
} else if (CN->getValue()+1 == 0) { // [X] += -1 -> DEC [X]
switch (Op0.getValueType()) {
default: break;
case MVT::i8:
addFullAddress(BuildMI(BB, X86::DEC8m, 4), AM);
return true;
case MVT::i16: Opc = TabPtr[1];
addFullAddress(BuildMI(BB, X86::DEC16m, 4), AM);
return true;
case MVT::i32: Opc = TabPtr[2];
addFullAddress(BuildMI(BB, X86::DEC32m, 4), AM);
return true;
}
}
}
addFullAddress(BuildMI(BB, Opc, 4+1),AM).addImm(CN->getValue());
return true;
}
@ -2365,6 +2431,9 @@ bool ISel::TryToFoldLoadOpStore(SDNode *Node) {
case MVT::i32: Opc = TabPtr[5]; break;
}
LoweredTokens.insert(TheLoad.getValue(1));
Select(Chain);
Select(TheLoad.getOperand(0));
X86AddressMode AM;
SelectAddress(TheLoad.getOperand(1), AM);